**AD629BRZ: Precision Difference Amplifier for High Common-Mode Voltage Applications**

In the realm of precision analog electronics, accurately measuring small differential signals riding on high common-mode voltages is a persistent challenge. This is a common scenario in industrial control systems, motor monitoring, power supply management, and battery stack monitoring, where voltages can far exceed the supply rails of typical operational amplifiers. The **AD629BRZ from Analog Devices** stands as a specialized solution engineered to excel in these demanding environments.

The AD629BRZ is a **high common-mode voltage difference amplifier** integrated into a single monolithic IC. Its primary function is to reject a large common-mode voltage—the voltage present on both inputs—while accurately amplifying the small differential voltage—the difference between the two inputs. The AD629BRZ is exceptionally adept at this, offering a common-mode voltage range of **±270V with a single ±15V supply**. This remarkable capability allows it to operate safely and precisely in high-voltage circuits without requiring external attenuation networks, which can introduce errors and complexity.

The device's architecture is based on a precision op-amp surrounded by a carefully trimmed integrated resistor network. This internal laser-trimming is key to its performance, ensuring **high accuracy and stability**. It boasts a typical common-mode rejection ratio (CMRR) of 93 dB (G = 1), which is crucial for rejecting noise and interference inherent in electrically noisy industrial environments. Furthermore, it features a low initial gain error of ±0.03% (for the B-grade) and low nonlinearity, guaranteeing that the amplified output is a faithful representation of the input differential signal.

A significant advantage of the AD629BRZ is its **simplified design-in process**. By integrating all critical components, it eliminates the need for designers to source and match high-precision external resistors. This not only saves board space but also enhances overall system reliability by minimizing drift errors caused by component mismatch over temperature and time. Its robust 8-pin SOIC package (BRZ denotes the tape and reel packaging for the SOIC) is suitable for a wide range of industrial and automotive applications.

Typical applications that benefit from the AD629BRZ's unique skill set include:

* **Current Shunt Monitoring:** Precisely measuring current by sensing the voltage drop across a shunt resistor in high-side configurations, even with hundreds of volts of common-mode voltage.

* **Ground Referenced Output:** For systems where the output must be referenced to ground despite the input signals floating at a high potential.

* **Fault Detection and Monitoring:** Isolating and measuring voltage differences in motor drives, circuit breakers, and power distribution systems to detect abnormal conditions.

* **Battery Stack Monitoring:** Accurately measuring the voltage of individual cells within a series stack of batteries for management and protection.

**ICGOODFIND:** The AD629BRZ is an **indispensable component for engineers** facing the challenge of high common-mode voltage measurement. Its integrated, precision-trimmed design delivers **exceptional accuracy, robustness, and simplicity**, making it a superior choice over discrete solutions. It effectively bridges the gap between high-voltage industrial sensors and low-voltage data acquisition systems, ensuring reliable and precise performance in the most demanding applications.

**Keywords:**

1. **Difference Amplifier**

2. **High Common-Mode Voltage**

3. **Precision Measurement**

4. **Current Shunt Monitoring**

5. **CMRR (Common-Mode Rejection Ratio)**